1. Field of the Invention
This invention is generally related to the use of enzymes and microorganisms for safely breaking down toxic compounds present at spill sites, in ground water, and at other locations where concern for the environment is of paramount importance. More particularly, the invention is directed to bioremediation of toxic compounds under anaerobic conditions.
2. Description of the Prior Art
Bioremediation involves the use of enzymes and microorganisms to breakdown waste products such that their impact on the environment is minimized. Bioremediation techniques have been used to treat organic compounds in the effluent from chemical plants, to degrade spills of oil and other fossil fuels, to remove sludge from pipes, to degrade organic matter at land fills, and for a wide variety of other applications. Efforts have been made to utilize bioremediation processes to convert toxic substances to non-hazardous forms. Bioremediation has the potential advantages of low cost and environmental soundness, and has, therefore, received much attention in the scientific and business communities.
Currently, most bioremediation processes are performed in aerobic conditions using aerobic microorganisms. However, many potential contamination sites, such as groundwater contamination, etc., that could benefit from a bioremediation clean-up process are anaerobic in character. Hence, the typical treatment scheme for groundwater contamination, for example, involves withdrawing the groundwater, aerating it, exposing it to aerobic microorganisms to detoxify chemical species within the groundwater, then returning the water to the ground. Employing such procedures can be expensive, and may cause the release of hazardous chemical constituents into the ambient air; thereby defeating the two chief advantages of using bioremediation processes.
Chlorinated compounds, such as trichloroethylene (TCE), decachlorooctahydro-1,3,4,-metheno-2H-cyclobuta(cd)pentalene-2-one(KEPONE) or chlorodecane, dichlorodiphenyltrichloroethane (DDT), and the like, are well known organic groundwater contaminants. Methane producing micro-organisms have been implicated in the reductive dehalogenation of multi-halogenated one-carbon compounds and ethylenes; however, the identity of which micro-organisms are responsible for dehalogenation and their mode of operation is not known. Krone et al., Biochemistry 28:4908-4914 (1989) and Biochemistry 30:2713-2719 (1991) have suggested that the reductive dehalogenation of one-carbon compounds may be catalysed by corrinoids which are present at high levels in methane producing microorganisms. Gantzer et al., Environ. Sci. Technol. 25:715-722 (1991), recently reported that vitamin B.sub.12 reductively dechlorinates TCE.